File clasps have been used for a long time to secure papers in files. Typically, the file clasps secure papers to a mounting flap of the folders through a pair of holes that are punched in the papers and mounting flap. Two types of file clasps are in widespread use. Both types include a thin metal band having a main body portion and two prong portions extending on either side of the main body portion. The prong portions are relatively inelastic but bendable--first, to positions at right angles to the main body portion for inserting the prongs through the holes in the papers and mounting flap; and second, to parallel positions with respect to the main body portion for securing the papers to the flap. The main body portion is made larger than the prong portions to provide a relatively rigid body from which the prong portions may be bent.
The main difference between the two widely used file clasps is that one uses a brace element which fits over the prongs before they are bent in place, and the other does not. The brace element is shaped similar to the main body portion and includes openings for receiving the prong portions. The brace is inserted over the prong portions when the prong portions are first bent at right angles. The prong portions are then bent again at right angles into alignment with the brace and are inserted through a pair of keepers carried on the brace to secure the prongs to the brace. The other known file clasp simply provides for bending the prong portions against the top surface of the papers.
The metal clasps are subject to having sharp edges or burrs which can cut into the papers they are securing or cause cuts in fingers handling the clasps. The prongs also tend to become rippled or misshapen with repeated use and no longer tightly secure the paper to the file.
U.S. Pat. No. 3,074,133 to J. L. Jones discloses a plastic file clasp having prong portions that are attached to each other by a pressure-sensitive adhesive. The adhesive material is secured to the plastic prong portions and a release coating on a flexible backing piece is used to protect the adhesive prior to use. The backing pieces with release coatings are removed prior to securing the prong portions together. Although the fastener is intended to be reusable, the adhesive bond is expected to deteriorate with repeated use until the prong portions no longer adequately secure papers in the file.